Why did banded iron formations form between 2.4 and 1.8 Ga?
A)The oceans became oversaturated in iron.
B)The oceans began to absorb large amounts of oxygen.
C)Cyanobacteria stopped using them as nutrients.
D)A mass extinction released iron into the oceans.

Question

Quizplus · Accepted Answer

Banded iron formations are primarily composed of iron and sedimentary rock layers that formed between 2.4 and 1.8 billion years ago. This period coincides with the Great Oxidation Event, where oxygen levels in the atmosphere rose significantly due to the evolution and proliferation of cyanobacteria. The high levels of oxygen allowed for the precipitation of iron out of the oceans, resulting in the formation of banded iron formations. Therefore, the best choice is B, as the oceans began to absorb large amounts of oxygen during this time period.

Why Did Banded Iron Formations Form Between 2